Concentrations Of Diphenylamine Research Articles

Understanding the biological impact of organic pollutants absorbed by nanoplastics

Many organisms are consuming food contaminated with micro- and nanoparticles of plastics, some of which absorb persistent organic pollutants (POPs) from the environment and acting as carrier vectors for increasing the bioavailability in living organisms. We recently reported that polymethylmethacrylate (PMMA) nanoparticles at low concentrations are not toxic to animal models tested. In this study, the toxicity of diphenylamine (DPA) incorporated PMMA nanoparticles are assessed using barnacle larvae as a model organism. The absorption capacity of DPA from water for commercially available virgin PMMA microparticles is relatively low (0.14 wt%) during a 48 h period, which did not induce exposure toxicity to barnacle nauplii. Thus, PMMA nanoparticles encapsulated with high concentrations of DPA (DPA-enc-PMMA) were prepared through a reported precipitation method to achieve 40% loading of DPA inside the particles. Toxicity of DPA-enc-PMMA nanoparticles were tested using freshly spawned acorn barnacle nauplii. The observed mortality of nauplii from DPA-enc-PMMA exposure was compared to the values obtained from pure DPA exposure in water. The mortality among the exposed acorn barnacle nauplii did not exceed 50% even at a high concentration of DPA inside the PMMA nanoparticles. The results suggest that the slow release of pollutants from polymer nanoparticles may not induce significant toxicity to the organism living in a dynamic environment. The impact of long-term exposure of DPA absorbed plastic nanoparticles need to be investigated in the future.

Influence of different levels and application method of Diphenylamine on production and quality of flower spike of Symphyotrichum novi- belgii L. cv. white Casablanca

The present study was carried out under field conditions at the Experimental Farm and the laboratory of Antoniades Research Branch, Horticulture Research Institute, A.R.C. Alexandria, Egypt during the two successive seasons of (2017- 2018) and (2018-2019). The aim of this work was to study the effects of different application levels of diphenylamine (DPA) at rates of (zero, 50, 100 and 200 ppm) by two application methods (soil drench and foliar spray) on vegetative growth, flowering characteristics, leaves photosynthetic pigments content and postharvest characteristics of Aster New York plants (Symphyotrichum novi-belgii cv. white casablanca). The plants were treated four times at 30, 60, 90 and 120 days from the final transplanting. The results showed that there was no significant difference between DPA application method or their combinations with its different concentrations in most recorded data. On the other hand, using different concentrations of DPA caused a significant effect on all studied characteristics. The highest plant height, leaf area, number of shoots/plant, leaves dry weight, inflorescence stalk diameter and dry weight, root volume and dry weight and leaves content of chlorophyll a, chlorophyll b and total carbohydrate was obtained after using DPA at 100 ppm. Also, this treatment caused the longest vase life, the highest final water uptake and floret opening percentage and the lowest loss of flower fresh weight percentage.

Prolong the vase life of flower spike of Aster (Symphyotrichum novi-belgii L.) by diphenylamine

ABSTRACT The present study was carried out at Antoniades Research Branch, Horticulture Research Institute, A.R.C. Alexandria, Egypt during the two successive seasons of 2017 and 2018 to study the effects of different concentrations and application methods of Diphenylamine (DPA) on the flower longevity of Aster New York plants (Symphyotrichum novi-belgii). Four concentrations of DPA (0, 25 , 50 and 100 ppm) and three application methods ( pulsing , foliar spray and holding solution ) were used in this experiment . The results showed that the highest significant vase life was obtained after application 50 ppm DPA as pulsing treatment for one hour , this treatment caused the lowest significant loss of flower fresh weight percentage (LFFW %), highest significant flower fresh weight/flower dry weight ratio (FWR), the highest relative fresh weight (RFW ) value and the highest significant reducing sugar content . Moreover, foliar spray treatment of DPA caused the highest significant increase of chlorophyll a and b content along the experiment period.

Toxicity of sediment-associated substituted phenylamine antioxidants on the early life stages of Pimephales promelas and a characterization of effects on freshwater organisms.

Substituted phenylamine antioxidants (SPAs) are high production volume chemicals that are incorporated into a variety of commercial products (e.g., polymers, dyes, lubricants). There are few data on chronic toxicity of SPAs to fish and no data on the toxicity of SPAs to the early life stages of fish. The physicochemical properties of SPAs would suggest that if they were to enter an aquatic ecosystem they would partition into sediment. Therefore, the present study focused on investigating the chronic effect of sediment-associated SPAs to the early life stages of the fathead minnow (Pimephales promelas). Eggs and larvae were exposed to sediment spiked with diphenylamine (DPA), N-phenyl-1-napthylamine (PNA), N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (DPPDA), or 4,4'-methylene-bis[N-sec-butylaniline] (MBA). The most sensitive endpoint for DPA, PNA, and DPPDA was total survival with 21-d median lethal concentrations (LC50s) based on concentration in overlying water of 1920, 74, and 35 μg/L, respectively. The most sensitive endpoint for MBA was growth with a 21-d median effective concentration (EC50) of 71 μg/L. The same endpoints were the most sensitive in terms of concentrations of DPA, PNA, DPPDA, and MBA in sediment (101, 54, 111, and 76 μg/g dry wt, respectively). Species sensitivity distributions (SSDs) were constructed for each SPA based on acute and chronic toxicity data generated in the present study and found in the literature. Overall, P. promelas was in the midrange of chronic sensitivity, with the most sensitive species being Tubifex tubifex. The SSDs indicate that DPA based on concentration in water is the least toxic to aquatic biota of the 4 SPAs investigated. The constructed SSDs indicate that a concentration in water and sediment of 1 μg/L and 1 μg/g dry weight, respectively, would be protective of >95% of the aquatic species tested. Environ Toxicol Chem 2017;36:2730-2738. © 2017 SETAC.

Isolation of a diphenylamine-degrading bacterium and characterization of its metabolic capacities, bioremediation and bioaugmentation potential.

The antioxidant diphenylamine (DPA) is used in fruit-packaging plants for the control of the physiological disorder apple scald. Its use results in the production of DPA-contaminated wastewater which should be treated before finally discharged. Biological treatment systems using tailored-made microbial inocula with specific catabolic activities comprise an appealing and sustainable solution. This study aimed to isolate DPA-degrading bacteria, identify the metabolic pathway of DPA and evaluate their potential for future implementation in bioremediation and biodepuration applications. A Pseudomonas putida strain named DPA1 able to rapidly degrade and utilize DPA as the sole C and N source was enriched from a DPA-contaminated soil. The isolated strain degraded spillage-level concentrations of DPA in liquid culture (2000 mg L(-1)) and in contaminated soil (1000 mg kg(-1)) and metabolized DPA via the transient formation of aniline and catechol. Further evidence for the bioremediation and biodepuration potential of the P. putida strain DPA1 was provided by its capacity to degrade the post-harvest fungicide ortho-phenylphenol (OPP), concurrently used by the fruit-packaging plants, although at slower rates and DPA in a wide range of pH (4.5-9) and temperatures (15-37 °C). These findings revealed the high potential of the P. putida strain DPA1 for use in future soil bioremediation strategies and/or as start-up inocula in wastewater biodepuration systems.

Micronucleus frequency in human lymphocytes after exposure to diphenylamine in vitro

Diphenylamine (DPA) is an antioxidant compound that occurs naturally in several vegetables. It is widely applied in agriculture for preservation of the quality of apples and pears, and used for controlling superficial scald, a disorder that renders fruits of a number of apple cultivars unfit for the market. Because of its anti-oxidative properties, DPA also has several industrial applications. The potential genotoxic effect of DPA on human lymphocytes has previously been investigated in only two studies, which focused on detection of chromosome aberrations and sister chromatid exchange, respectively. In the present analysis, we evaluated micronucleus (MN) formation in freshly isolated human peripheral lymphocytes exposed to different concentrations (0.625, 1.25, 2.50, 5.0 and 10.0μg/ml) of DPA. Peripheral venous blood was collected from ten healthy subjects, and a total of 10,000 bi-nucleated cells were analyzed. Results indicated that DPA significantly increased the micronucleus frequency at concentrations of 1.25μg/ml and higher. Significant differences in the MN frequency were also found between the lower dose (0.625μg/ml) and all other doses tested, with the exception of 1.25μg/ml. Our results indicate a potential cytogenetic effect of DPA on human cells in vitro and require further in vivo studies to clarify the actual genotoxicity of this compound and the consequent risks for human health.

<i>In Situ</i> UV–Vis Spectroelectrochemical Studies on the Copolymerization of Diphenylamine and <i>o</i>-Phenylenediamine

The in situ ultraviolet-visible (UV-Vis) spectroelectrochemical study on the copolymerization of diphenylamine (DPA) and o-phenylenediamine (OPD) has been performed at a constant potential of 0.8 V using indium tin oxide (ITO)-coated glass electrodes as working electrode. And also, as a comparison, the electrochemical homopolymerizations of DPA and OPD have been investigated by using the in situ spectroelectrochemical technique. The intermediate species generated during the electrochemical homopoly-merization of DPA and OPD, and the copolymerization of DPA with OPD have been identified by using the in situ spectroelectrochemical procedure. The results reveal the formation of an intermediate in the initial stage of copolymerization through the cross-reaction of the cation radicals of DPA and OPD, and the absorption peak located at 538 nm in the UV–Vis spectra is assigned to this intermediate. To further investigate the copolymerization of DPA with OPD, cyclic voltammetry (CV) has been used to study the electrochemical homopolymerization of DPA and OPD and also the copolymerization of DPA and OPD with different concentration ratios in solution. The different voltammetric characteristics between the homopolymerization and copolymerization processes exhibit the occurrence of the copolymerization, and the difference between the copolymerization of DPA and OPD with different concentration ratios shows the dependence of the copoly-merization on the concentrations of DPA and OPD. The copolymer has also been characterized by Fourier transform infrared spectroscopy (FT-IR).

Electrochemical synthesis and spectroelectrochemical behavior of poly(diphenylamine-co-4,4′-diaminodiphenyl sulfone)

The electroactive copolymer of diphenylamine (DPA) and 4,4′-diaminodiphenyl sulfone (DADPS) was synthesized electrochemically in 4 M H 2SO 4 and ethanol medium. Both electrochemical synthesis and characterization of the copolymer deposited on a glassy carbon electrode (GCE) were carried out using cyclic voltammetry. The voltammograms exhibited different patterns of behavior with different feed concentrations of DPA. Equimolar concentrations of DPA and DADPS demonstrated very efficient growth of the copolymer film on the surface of the GCE. The copolymer exhibited high solubility in dimethyl sulfoxide (DMSO). The scan rate exerted little-effect on this GCE copolymer film, revealing the film's excellent electroactive adherent properties. The effect of pH on the copolymer film showed that the polymer was electrochemically active up to pH 7.0. Spectroelectrochemical analysis of the copolymer film, carried out on an indium tin oxide (ITO) plate, showed multicolor electrochromic behavior when the applied potential was changed. The copolymer was characterized by FTIR and 1H NMR spectral data. The surface morphology was studied using SEM analysis, the grain size of the copolymer was measured using XRD studies and was found to be 56 nm. The electrical conductivity of the copolymer was 2.65 × 10 −2 S cm −1, as determined using a four-probe conductivity meter.

Preferential Incorporation of Coloured-carotenoids Occurs in the LH2 Complexes From Non-sulphur Purple Bacteria Under Carotenoid-limiting Conditions

The effect of growing Rhodopseudomonas (Rps.) acidophila and Rps. palustris in the presence of different concentrations of the carotenoid (Car) biosynthetic inhibitor diphenylamine (DPA) has been investigated. Growth with sub-maximal concentrations of DPA induces Car limitation. The exact response to DPA is species dependent. However, both Rps. acidophila and Rps. palustris respond by preferentially incorporating the limiting amount of coloured Cars into their LH2 complexes at the expense of the RC-LH1 complexes. As inhibition by DPA becomes more severe there is an increase in the percentage of Cars with reduced numbers of conjugated C=C bonds. The effect of this changed Car composition on the structure and function of the antenna complexes has been investigated using absorption, fluorescence, CD and Raman spectroscopies. The results show that although the presence of Car molecules is important for the stability of the LH2 complexes that the overall native structure can be maintained by the presence of many different Cars.

Diphenylamine and Diphenylamine Derivative Content of `Granny Smith' Peel: Influence of Ethylene Action and Regular or Controlled Atmosphere Storage Duration

Diphenylamine (DPA) is used for superficial scald control in apple fruit. A number of DPA derivatives resulting from C-nitration, C-hydroxylation, O-methylation, and N-nitrosation can be present in DPA-treated apple fruit after storage. The presence of the compounds may be indicative of metabolic processes that lead to scald development. Therefore, apple peel DPA and DPA derivative content in fruit treated at harvest with DPA or DPA plus 1-methylcyclopropene (1-MCP) was assayed upon removal of fruit from controlled atmosphere (CA) and regular atmosphere (RA) storage and during a 14-d post-storage ripening period. Apples were also treated at harvest with different concentrations of DPA and assayed after 6 months CA storage to confirm recovery of DPA and DPA derivatives is linear over a wide concentration range. Harvest maturity notably affected peel DPA and 4-hydroxydiphenylamine (4OHDPA) content. Post-storage ripening, 1-MCP treatment, and CA storage had varied affects on DPA derivative content, suggesting reactive oxygen or nitrogen species, such as •OH, •NO, and •NO2, or enzyme catalyzed reactions may be generated during ripening and senescence related physiological processes. Consistent correlations between scald incidence and content of specific derivatives were not observed.

UV–vis spectroscopy for following the kinetics of homogeneous polymerization of diphenylamine in p-toluene sulphonic acid

Kinetics of chemical oxidative polymerization of diphenylamine (DPA) was followed in aqueous 1 M para-toluene sulphonic acid ( p-TSA) using potassium peroxomonosulphate (PMS) or peroxodisulphate (PDS), independently as an oxidant. The medium was found to be homogeneous and became dark green in colour during the course of polymerisation. The course of polymerization was followed by UV–vis spectroscopy. Rate of polymerization ( R p) was determined for various conditions by following the absorbance values corresponding to poly(diphenylamine) (PDPA) for different concentrations of DPA and PMS or PDS at various time intervals of polymerization. The observed dependences of DPA, PDS or PMS on R p were used to deduce rate equations for PDS or PMS initiated polymerization of DPA. The rate constant for the formation of poly(diphenylamine), was estimated. In situ spectroelectrochemical studies on the polymerization of DPA were also carried out on an ITO electrode in 1 M p-TSA. The results are in accordance with the intermediates suggested in chemical oxidative polymerization.

Contamination of Apple Fruit with Diphenylamine During Storage

Apple fruit are treatmented with diphenylamine (DPA) in the form of a postharvest dip to prevent the development of storage scald. However, DPA residues have been detected on apples not treated with DPA, which is problematic in markets where DPA residues are not acceptable. The objective of this study was to identify sources of DPA contamination and evaluate the effectiveness of ozone to reduce contamination. Concentrations of DPA in the atmosphere of commercial storage rooms was monitored during the storage season and the adsorption of DPA onto wood and plastic bin material, plastic bin liners, foam insulation, and apple fruit was assessed. DPA was sampled from headspace with solid phase micro extraction using 65 μm polyacrylate micro fibers and analyzed using GC-MS. The effectiveness of gaseous treatments of 300 and 800 ppb ozone to reduce DPA contamination on apple fruit and bin material was also determined. DPA was found to volatilize from treated apples and bins into the storage room air, where it was adsorbed onto storage room walls, bins, bin liners and other fruit. DPA was found in the atmosphere of storage rooms containing apples that were not treated with DPA. Wood and plastic bin material, bin liners, and foam insulation all had a high affinity for DPA and were determined to be potential sources of contamination. Ozone reacted with DPA and following gaseous ozone treatments, off-gassing of DPA from wood and plastic bin material and bin liners was reduced. However, ozone was not effective in removing all DPA in contaminated materials and was ineffective in removing DPA from contaminated apples. Due to the pervasive and persistent nature of DPA, fruit should be handled and stored in facilities where DPA is not used to prevent contamination of fruit.

Electrochemical, spectroelectrochemical and spectroscopic evidences for copolymer formation between diphenylamine and m-toluidine

Electrochemical copolymerization of diphenylamine (DPA) with m-toluidine (MT) was carried out for different molar feed ratios of DPA in 4 M H 2SO 4 using cyclic voltammetry. Cyclic voltammogram (CV) of the deposited copolymer film was also recorded in 4 M H 2SO 4. CVs recorded during polymerization of mixture of DPA and MT clearly reveals deposition of copolymer with different proportions of DPA unit in it. The CV characteristics show dependence on the molar feed concentrations of DPA or MT. UV-Vis spectroelectrochemical studies reveal the formation of intermediates/copolymer having units of DPA and MT in the backbone structure with a new characteristic band around 580 nm. Copolymers were synthesized for different molar concentration feed ratios of DPA and the molar composition of DPA and MT units in the copolymers were determined by UV-Vis spectroscopy. Reactivity ratios of DPA and MT were computed by using Fineman–Ross and Kelen–Tudos methods and correlated with spectroelectrochemical results. The copolymers were further characterized by FT-IR spectroscopy and thermogravimetric analysis.

Electrochemical Copolymerization of Diphenylamine and Anthranilic Acid with Various Feed Ratios

Electrochemical copolymerization of diphenylamine (DPA) with anthranilic acid (AA) was performed in aqueous 4 M solution for different feed ratios of DPA using cyclic voltammetry. The copolymer film was grown for different numbers of cycles, and feed ratios of DPA. Electrochemical homopolymerization of DPA was also carried out under identical conditions and compared. A growth equation of the deposited films in terms of concentrations of DPA and AA and is deduced as by utilizing the charge associated for film deposition. The copolymer compositions were determined by X-ray photoelectron spectroscopy. Reactivity ratios of DPA and AA were computed by using Fineman-Ross and Kelen-Tüdös methods. © 2001 The Electrochemical Society. All rights reserved.

Kinetic modelling of the concentrations of the stabilizer DPA and some of its consecutive products as function of time and temperature

By kinetic modelling of the possible reactions of diphenylamine (DPA) and its nitrated consecutive products used to stabilize cellulose nitrate (CN), one can get reactivities for the nitrated DPA compounds for the situation inside a real CN formulation and therewith determine their stabilizing contribution. Concentration data of DPA and seven of its consecutive products have been determined by HPLC from isothermal ageing of a CN formulation at temperatures between 65 and 90°C for up to 344 days. A comparison between the modelling presented and modellings published in the literature using the steady-state approximation is made. The steady-state approximation oversimplifies the stabilizer reaction behaviour in a CN formulation. From the applied modelling the question about N–NO–DPA as a key intermediate can be answered.

Effect of inhibitors on the ubiquinone binding capacity of the primary energy conversion site in the Rhodobacter capsulatus cytochrome bc(1) complex.

A key issue concerning the primary conversion (Q(O)) site function in the cytochrome bc(1) complex is the stoichiometry of ubiquinone/ubihydroquinone occupancy. Previous evidence suggests that the Q(O) site is able to accommodate two ubiquinone molecules, the double occupancy model [Ding, H., Robertson, D. E., Daldal, F., and Dutton, P. L. (1992) Biochemistry 31, 3144-3158]. In the recently reported crystal structures of the cytochrome bc(1) complex, no electron density was identified in the Q(O) site that could be ascribed to ubiquinone. To provide further insight into this issue, we have manipulated the cytochrome bc(1) complex Q(O) site occupancy in photosynthetic membranes from Rhodobacter capsulatus by using inhibitor titrations and ubiquinone extraction to modulate the amount of ubiquinone bound in the site. The nature of the Q(O) site occupants was probed via the sensitivity of the reduced [2Fe-2S] cluster electron paramagnetic resonance (EPR) spectra to modulation of Q(O) site occupancy. Diphenylamine (DPA) and methoxyacrylate (MOA)-stilbene are known Q(O) site inhibitors of the cytochrome bc(1) complex. Addition of stoichiometric concentrations of MOA-stilbene or excess DPA to cytochrome bc(1) complexes with natural levels of ubiquinone elicits the same change in the [2Fe-2S] cluster EPR spectra; the g(x)() resonance broadens and shifts from 1. 800 to 1.783. This is exactly the same signal as that obtained when there is only one ubiquinone present in the Q(O) site. Furthermore, addition of MOA-stilbene or DPA to the cytochrome bc(1) complex depleted of ubiquinone does not alter the [2Fe-2S] cluster EPR spectral line shapes, which remain indicative of one ubiquinone or zero ubiquinones in the Q(O) site, with broad g(x)() resonances at 1. 783 or 1.765, respectively. The results are quite consistent with the Q(O) site double occupancy model, in which MOA-stilbene and DPA inhibit by displacing one, but not both, of the Q(O) site ubiquinones.

Decomposition of diphenylamine in nitrocellulose based propellants—I. Optimization of a numerical model to concentration-time data for diphenylamine and its primary degradation products determined by liquid chromatography with dual-amperometric detection

The consumption of diphenylamine (DPA) in two nitrocellulose (NC) based propellants subjected to a heat storage test at 85° has been studied. A previously developed method based on reversed-phase liquid chromatography with dual-amperometric detection was used to monitor the concentrations of DPA, 2-nitro-DPA and 4-nitro-DPA during the test. A numerical model based on first order rate equations was fitted to the obtained analytical data with the use of a specially written curve fitting program. The model implemented in the program describes the initial nitrosation and nitration steps of DPA in aging NC propellants. The use of matrices in the calculation of concentration-time (CT) curves enables the introduction of a general algorithm which can be readily changed in order to simulate any system of first order reactions. The program can therefore be used in other applications such as mechanistic studies in organic synthesis. The general simulation algorithm allows inclusion of unknown (not analysed) components in the reaction mechanism. In this application, it was possible to simulate the course of N-nitroso-DPA which is not detectable by the amperometric principle.

Post‐harvest application of diphenylamine and ethoxyquin for the control of superficial scald on Bramley's seedling apples

AbstractRecent changes in the antioxidant regulations in the UK and the need to evaluate the effectiveness of scald control chemicals in the presence of other post‐harvest chemicals led to a comparative study of the effects of diphenylamine (DPA) and ethoxyquin on scald development in Bramley's Seedling apples. A range of concentrations (1000–4000 mg litre−1 a.i.) of DPA completely controlled scald on Bramley apples kept in controlled atmosphere storage for 241 days; ethoxyquin at equivalent rates was less effective. Only partial control of scald was achieved with 500 mg litre−1 a.i. DPA. None of the treatments injured the fruit. Control of scald by 2000 mg litre−1 a.i. DPA or ethoxyquin was not impaired by adding thiophanate‐methyl (l g litre−1 a.i.) or calcium chloride (10 g litre−1) although the measure of control was reduced when both fungicide and calcium chloride were added. Calcium chloride caused lenticel injury which was aggravated by adding ethoxyquin but reduced by incorporating DPA. The concentrations of ethoxyquin and DPA residues on the fruit immediately after treatment were within the limits required by UK legislation (see reference 1) of 3 mg kg−1 and 10 mg kg−1, respectively, even where 4000 mg litre−1 had been applied. An initial residue concentration of 2.3 mg kg−1 DPA was associated with complete control of scald. Residue levels, particularly of DPA, declined rapidly during the first month of storage.

Effect of Light on Carotenoid and Riboflavin Production by the Fungus Cephalosporium diospyri

SUMMARY: Carotenoids were produced in the mycelial form of Cephalosporium diospyri only after exposure to light of wavelength < 500 nm, and production occurred in three stages. The initial photoinduction required light and was temperature-independent. Both subsequent dark stages, consisting of a lag period and of actual synthesis of carotenoids, were temperature-dependent. All steps had an absolute requirement for oxygen. Filtrates from dark-grown cultures contained ribo-flavin, while lumichrome was present in filtrates from light-grown cultures. Intracellular riboflavin levels were the same in both. Concentrations of diphenyl-amine which inhibited carotenogensis in light-grown cultures also inhibited extracellular production of riboflavin by dark-grown organisms. Several compounds with known photomimetic properties were tested on dark-grown mycelia, but pigmentation was induced only in plate cultures containing p-hydroxymercuri-benzoate. These pigments had the appearance of carotenoids, but have not been chemically characterized.